Ankle Fracture Stability-based Classification

• Main Authors: James Michelson MD, John Delaney MD
• Format: Article
• Language: English
• Published: SAGE Publishing 2018-09-01
• Series: Foot & Ankle Orthopaedics
• Online Access: https://doi.org/10.1177/2473011418S00348

Category: Trauma Introduction/Purpose: Rotational ankle fractures are common in orthopaedic surgery, however existing classification systems are mostly descriptive in nature and do not explicitly guide surgical decision-making. A Stability-Based classification was developed recently to provide a more prognostic classification. The purpose of this study was to compare the reproducibility of existing ankle fracture classifications, and determine the ability of the Stability-Based classification to predict clinical treatment. Methods: One hundred ninety-three consecutive ankle fractures treated at our institution were retrospectively analyzed. Rotational type injury patterns in patients >18 years old were included. None of the subjects were clinically treated or evaluated by the study authors. The fractures were treated by attending physicians who were unaware of the Stability-Based classification system. Pathologic fractures were excluded. Three observers classified injury radiographs using the Lauge-Hansen, Weber/AO, and Stability-Based classifications systems. Reproducibility (inter-observer variation) of each classification system was calculated using kappa statistics. Prognostic values were evaluated by calculating the area under the curve (AUC) for the ROC curves (using surgery as the positive outcome) for each classification. Results: The Stability-Based classification was showed the excellent reproducibility (kappa .938, 95% CI .921-.952), along with the Weber/AO classification (kappa .97, 95% CI .961-.976), while the Lauge-Hansen had the lowest reproducibility (kappa .74, 95%CI .664-.795). The AUC for the three classifications were .883 (95%CI .852-.914), .626 (95%CI .576-.675), and .698 (95%CI .641-.755), respectively (Figure 1). The AUC was significantly better for the Stability-Based classification compared to the other 2 classifications (p<.001). Conclusion: The AO/Weber classification had excellent reproducibility, but did not predict the need for surgical stabilization accurately. In contrast, the Stability-Based classification system was both highly reproducible (kappa .938) with excellent prognostic ability to identify patients who got surgery (AUC .883). Furthermore, there were no patients who were classified as stable who failed non-operative treatment. The Stability-Based classification was found to have superior prognostic capacity compared to both the Lauge-Hansen and AO/Weber classification systems. This extends earlier studies by showing the reproducibility of the Stability-Based classification system and directly demonstrating its prognostic superiority to other classification systems.